Alternator problem solved!

[cougar]

I won, finally. My 91 lives on. Okay, here's the deal. Last fall my alternator voltage started climbing, so I replaced the regulator. No help, just added the needle wiggle at idle. Tried 2 more regulators and no hope. Replace the regulator connector and the wires to the alternator. Still no good. Replaced the alternator. Still n/g Well, driving down the road I noticed the needle pulsing and first thought Okay it's done. I wiggled the key and it came back to life, hummm It happened again, so I repeated my umm test and repeated my results. So, I bought a new ignition switch to try and it was defective, but it did prove my suspicions. Got another switch, grabbed the wrong screw and stripped the hole in the column Taped up the hole to an 8-32, put the new switch in and it bound up when I tightened the screws I loosened the screws and the bind went away so I just shimmed the switch and went on my frustrated, but merry way.
Conclusion: A voltage drop through the ignition switch could be the cause of your alternator problems.

[Tacoclaw]

Here's what Ive found. My truck was doing the volt gauge "wiggle wiggle" thing. All the lights would flicker, etc...I finally went out and did some real diagnosis to figure out why, since my previous truck did the same thing. After several tests of wiring, and consulting the factory service manual, I found a voltage drop of 0.8 volts to the blue wiring to the regulator. Tracing the wiring in the manual, I decided to check the fuses that are common with this circuit. Fuse 11, 12, and 13 all had the same drop, their source is one of the "key on" circuits in the ignition switch. I suspect the switch is the culprit, but I haven't checked that far yet. I have however used a jumper wire from the battery to the regulator, to try the charging system. It functions perfectly with the jumper wire attached, and pulses with it removed.
There is still the possibility that the source that FEEDS the ignition switch is weak. The feed originates from the heavy cable from the alternator/battery connection, thru a fuse link, thru the bulkhead connector, than to the ignition switch.
I will post my final findings when I confirm the repair. Hope this info helps.